The fields of nanoscience and nanotechnology generally concern the synthesis, fabrication and use of nanoelements and nanostructures at atomic, molecular and supramolecular levels. The nanosize of these elements and structures offers significant potential for research and applications across the scientific disciplines, including materials science, physics, chemistry, computer science, engineering and biology. Biological processes and methods, for example, are expected to be developed based entirely on nanoelements and their assembly into nanostructures. Other applications include developing nanodevices for use in semiconductors, electronics, photonics, optics, materials and medicine, and the like.
In particular electronic elements can be fabricated from nanomaterials using certain selected techniques that are modified to handle and manipulate the nanoscale material. One class of materials that has garnered considerable interest are carbon nanotubes. A carbon nanotube has a diameter on the order of nanometers and can be several micrometers in length. These nanoelements feature concentrically arranged carbon hexagons. Carbon nanotubes can behave as metals or semiconductors depending on their chirality and physical geometry.
Although carbon nanotubes have been assembled into different nanostructures, only limited nanotools and fabrication methods for their assembly have been developed. One obstacle has been the manipulation of individual nanoelements, which is often inefficient and tedious. This problem is particularly challenging when assembling complex nanostructures that require selecting and ordering millions of nanoelements across a large area.
Current nanostructure assembly has focused on dispersing and manipulating nanoelements using atomic force or scanning tunneling microscopic methods. Although these methods are useful for fabricating simple nanodevices, neither is practical when selecting and patterning, for example, millions of nanoelements for more complex structures. As an alternative, lithographic methods have been developed to modify substrates used for assembling nanoelements. Examples of these lithographic methods include, but are not limited to, electron-beam, ion-beam, extreme ultraviolet and soft lithographies. These methods, however, remain incapable of manipulating individual nanoelements. The development of nanomachines or “nanoassemblers” which are programmed and used to order nanoelements for their assembly holds promise, although there have been few practical advancements with these machines to date.
Self-assembly is a method for nanodevice fabrication that does not require nanoelements to be individually manipulated. In self-assembly, nanoelements are designed to naturally organize into patterns by atomic, molecular and supramolecular particle interactions. Self-assembled monolayers, for example, are formed by the spontaneous arrangement of molecules into monomolecular layered structures. These structures can be stabilized by van der Waals forces or other forms of noncovalent bonding. Self-assembled monolayers, however, have been problematic when used to transfer nanoelements from one nanosubstrate to a recipient substrate. Although particle interactions can be modified to affect their transport, optical and electrical properties, controlling nanoelement orientation is also a challenge in self-assembly methods. Similarly, nanoscience has been incapable of manipulating particle interactions to reproducibly assemble hundreds of nanodevices.
Further, conventional manufacturing techniques have failed to integrate nanoscale processes and nanomaterials into products. Conventional prior art approaches such as inkjet printing, gravure type printing, and screen printing have been used to create structures using nanomaterials. However, these processes are quite slow, are not readily scalable, do not provide sufficient high rate throughput and typically only provide micron scale resolution.